Motors, particularly gas powered motors or automobile engines, create a significant amount of vibration. For example, the action of the cam shaft creates torsional vibration. Torsional vibration can be reduced by using a vibration dampener. Typically the dampener mounts to the drive shaft and includes an annular weight fixed to a hub by an elastomeric member. A pulley may ride on the exterior surface of annular weight. Regardless, it is important that the weight not slip relative to the hub.
The elastomeric member or ring can be formed in a number of different ways. The elastomer can be injection molded between the annular weight and the hub and cured in place. This is by far the strongest bond that can be achieved in the torsional vibration dampener. Alternately a pre-formed or pre-cured elastomeric ring can be forced between the annular weight and the hub. Adhesive can be pre-applied to either surface to improve the bond between the metal weight and the metal hub.
The least expensive torsional vibration dampener simply uses a pre-cured elastomeric member which is compressed and force-fitted between the annular ring and hub. The resulting compression provides a strong bond between the annular ring and hub and prevents relative slippage. However, as this heats, the elastomeric member softens and slipping is a more significant problem.
The concern with relative movement between a elastomeric member and a metal member can be found in other applications such as the rubber bushing on a shock absorber.
The present invention is premised on the realization that the bond between a previously cured elastomeric member and a metal surface can be significantly enhanced by phosphating the metal surface prior to compression fitting the elastomeric member to the metal member.
Further with certain elastomeric members the bond strength between the metal surface and the elastomeric member can increase as the composite structure is heat aged as might occur during use. The phosphated surface actually promotes a bond between the metal surface and the elastomeric member particularly with respect to pre-cured EPDM and pre-cured ethylene acrylates.
The objects and advantages of the present invention will be further appreciated in light of the following detailed description and drawings in which: